In the co-pending application of John G. Stevenson, Ser. No. 08/236,800, filed May 2, 1994, and assigned to applicants' assignee, a system is described in which a path test command is launched in a network, following a path determined in the same way as a normal data transfer from a source to a destination in a so-called connectionless network, that is, in a network in which the transmission path is not predetermined prior to the transmission of data. At each node encountered along the connection path, the path test command initiates a path test identifying that node and the current time. These results of the path test are sent back to the node initiating the path test command. Thus, as the path test command traverses the data path, a sequence of test results flow from each of the nodes encountered along the path back to the originating node. As noted in the aforementioned patent application, these results can be combined at the originating node to determine the response time of the entire path from source to destination, the response time of each leg along this path, and hence the identification of congestion points in the path. If the destination node is never reached, the returned test results serve to identify the first encountered failed transmission leg or node.
In order to implement the path test of the afore-mentioned patent application, each resource encountered along the transmission path traversed by the path test must be modified so as to properly respond to the path test command, that is, to generate the path test results, to formulate and transmit these path test results into a message, and to return this message back to the originating source node. The implementation of this prior art solution to the problem of testing data paths therefore involves the considerable modification of each and every resource included in the network, thus significantly increasing the cost and complexity of the network.
Many connection oriented (as opposed to connectionless) packet network routing mechanisms pre-calculate the path to be followed by data packets transmitted from a source node to the destination node such as that disclosed in H. Ahmadi et al. U.S. Pat. No. 5,233,604, granted Aug. 3, 1993. In one such connection oriented system, the IBM Systems Network Architecture (SNA) system, a topology data base containing current information about the state of all of the resources of the network is maintained at each node. The information in this data base is then used to calculate an optimal route between the originating node and the destination node. These routes are then saved to control the actual routing of data packets to be transmitted from this originating node along the pre-calculated route to the destination node. In order to test the route or path actually used by the data packets, some mechanism, such as SNA, is necessary to insure correspondence between the data route and the test route.